50 years ago, IBM created mainframe that helped send men to the Moon

System/360 brought new era of compatibility, and its programs still run today.

50 years ago today, IBM unveiled the System/360 mainframe, a groundbreaking computer that allowed new levels of compatibility between systems and helped NASA send astronauts to the Moon.

While IBM had been making its 700 and 7000 Series mainframes for more than a decade, the System/360 "ushered in an era of computer compatibility—for the first time, allowing machines across a product line to work with each other," IBM says. "It was the first product family that allowed business data-processing operations to grow from the smallest machine to the largest without the enormous expense of rewriting vital programs... Code written for the smallest member of the family had to be upwardly compatible with each of the family’s larger processors. Peripherals such as printers, communications devices, storage, and input-output devices had to be compatible across the family."

Before the System/360, "businesses bought a computer, wrote programs for it, and then when it got too old or slow they threw it away and started again from scratch," IBM spokesperson Barry Heptonstall told the BBC.

Text of the original press release issued by IBM's Data Processing Division on April 7, 1964 is on IBM's site. The systems would sell for $133,000 to $5.5 million, or could be rented for $2,700 to $115,000 a month. The least expensive started shipping in 1965, with higher-end ones being delivered in 1966.

Despite the high price, there was much excitement. "More than 100,000 businessmen in 165 American cities today attended meetings at which System/360 was announced," IBM said at the time. Company President Thomas J. Watson Jr. called the System/360 IBM's most important product announcement ever and said it "represents a sharp departure from concepts of the past in designing and building computers." The initial announcement didn't actually call it a "mainframe," a word IBM wouldn't embrace for many years.

IBM received more than 1,000 orders in the month after the announcement and another 1,000 over the ensuing four months. The specs were impressive for the time. "Introduction of the 8-bit byte, over the prevalent 6-bit standard, made it easier to handle both business information processing and scientific data processing," an IBM retrospective says. "The six models announced in April of 1964 had a performance range of roughly 25-to-1, with the largest model being about 25 times more powerful than the smallest. The smallest model could perform 33,000 additions per second; the largest more than 750,000 additions per second."

System/360 machines were crucial for NASA's Apollo missions. "Apollo flights had so much information to relay, that their computers had to report in an electronic form of shorthand," IBM says. "Even in shorthand, however, it took a circuit capable of transmitting a novel a minute to get the information to NASA’s Manned Spacecraft Center—now the Johnson Space Center—in Houston, Texas. Receiving this enormous amount of data was a powerful IBM computer whose sole task was to translate the shorthand into meaningful information for Apollo flight controllers. The IBM System/360 computer absorbed, translated, calculated, evaluated, and relayed this information for display. It was one of five System/360 machines used by NASA for the Apollo 11 mission. The same System/360 computer that processed the data for the first lunar landing from 240,000 miles away in Houston also calculated the liftoff data needed by astronauts Neil Armstrong and Edwin 'Buzz' Aldrin to rendezvous back with the command module piloted by Michael Collins for the flight back to Earth."

System/370 started to replace System/360 in the early 1970s as IBM continued to dominate the computing market. Even today, IBM mainframes are big business, raking in $1.1 billion in revenue in the most recent quarter.

Modern IBM mainframes go by the name System z, which maintains compatibility all the way back to System/360. "The need to support applications of varying ages imposes a strict compatibility demand on mainframe hardware and software, which have been upgraded many times since the first System/360 mainframe computer," IBM says. "Applications must continue to work properly. Thus, much of the design work for new hardware and system software revolves around this compatibility requirement."

The result is that "Programs for the original System/360s can still run, sometimes with only slight modification, on IBM mainframes today," IDG News Service reporter Joab Jackson noted. While complete compatibility over many decades and system changes isn't possible, IBM tries to give users at least a year's warning before they'd need to make software changes.

According to IBM, "A standard interface made it easy for businesses to attach peripheral products to the System/360 processors. Third-party suppliers and manufacturers soon offered plug-compatible peripheral products."

Five System/360 machines were used by NASA for the Apollo 11 mission to the Moon in 1969. This System/360 Model 75 in Houston "calculated liftoff data needed by astronauts Neil Armstrong and Edwin 'Buzz' Aldrin for the flight back to Earth."

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Modern IBM mainframes go by the name System z, which maintains compatibility all the way back to System/360. "The need to support applications of varying ages imposes a strict compatibility demand on mainframe hardware and software, which have been upgraded many times since the first System/360 mainframe computer," IBM says. "Applications must continue to work properly. Thus, much of the design work for new hardware and system software revolves around this compatibility requirement."

The result is that "Programs for the original System/360s can still run, sometimes with only slight modification, on IBM mainframes today," IDG News Service reporter Joab Jackson noted. While complete compatibility over many decades and system changes isn't possible, IBM tries to give users at least a year's warning before they'd need to make software changes.

That's what I find most impressive out of anything.50 years of backwards compatibility.

Modern IBM mainframes go by the name System z, which maintains compatibility all the way back to System/360. "The need to support applications of varying ages imposes a strict compatibility demand on mainframe hardware and software, which have been upgraded many times since the first System/360 mainframe computer," IBM says. "Applications must continue to work properly. Thus, much of the design work for new hardware and system software revolves around this compatibility requirement."

The result is that "Programs for the original System/360s can still run, sometimes with only slight modification, on IBM mainframes today," IDG News Service reporter Joab Jackson noted. While complete compatibility over many decades and system changes isn't possible, IBM tries to give users at least a year's warning before they'd need to make software changes.

That's what I find most impressive out of anything.50 years of backwards compatibility.

Modern IBM mainframes go by the name System z, which maintains compatibility all the way back to System/360. "The need to support applications of varying ages imposes a strict compatibility demand on mainframe hardware and software, which have been upgraded many times since the first System/360 mainframe computer," IBM says. "Applications must continue to work properly. Thus, much of the design work for new hardware and system software revolves around this compatibility requirement."

The result is that "Programs for the original System/360s can still run, sometimes with only slight modification, on IBM mainframes today," IDG News Service reporter Joab Jackson noted. While complete compatibility over many decades and system changes isn't possible, IBM tries to give users at least a year's warning before they'd need to make software changes.

That's what I find most impressive out of anything.50 years of backwards compatibility.

"Take men to the moon." Not bring. I expect my friends to not know the difference, the state of American's command of the English language being what it is today. But a professionally edited journal should at least get it right in the headline, for crying out loud.

"Take men to the moon." Not bring. I expect my friends to not know the difference, the state of American's command of the English language being what it is today. But a professionally edited journal should at least get it right in the headline, for crying out loud.

For instance, in a situation where someone has knocked on your door and you shout reassurance to them to let them know you're on your way to the door from somewhere else, what you say in Spanish is Voy ('I'm going'), because you're moving away from where you're at. In English what you say is I'm coming, because you're moving toward the place your addressee is at; in English you can take either the speaker's or the addressee's position as the terminus ad quem for come, as well as the terminus a quo for go.

The ties are a little narrow but the suits still look good, fifty years later.

With tiepins as a mandatory accessory - one time when our Prime mini was being serviced by the duly authorized & expensive man a jovial executive from our side leaned over for a look, his un-pinned tie dangling into the works. Serviceman yelled with horror - nice dry aircon so many kV of static electricity across tie about to slap around a board of big leggy CMOS chips. Us lowly operators were most impressed - didn't know you even could yell at our execs and live, but when you're from a Big Computing Firm you can!

The ties are a little narrow but the suits still look good, fifty years later.

With tiepins as a mandatory accessory - one time when our Prime mini was being serviced by the duly authorized & expensive man a jovial executive from our side leaned over for a look, his un-pinned tie dangling into the works. Serviceman yelled with horror - nice dry aircon so many kV of static electricity across tie about to slap around a board of big leggy CMOS chips. Us lowly operators were most impressed - didn't know you even could yell at our execs and live, but when you're from a Big Computing Firm you can!

I STILL wear tie bars! Tie tacs are nice and small but I don't like the idea if sticking one through my tie. And yes, they do serve a safety function.

[edit: meant to say tie bar, not tie pin which is the same thing as a tie tac!]

The ties are a little narrow but the suits still look good, fifty years later.

With tiepins as a mandatory accessory - one time when our Prime mini was being serviced by the duly authorized & expensive man a jovial executive from our side leaned over for a look, his un-pinned tie dangling into the works. Serviceman yelled with horror - nice dry aircon so many kV of static electricity across tie about to slap around a board of big leggy CMOS chips. Us lowly operators were most impressed - didn't know you even could yell at our execs and live, but when you're from a Big Computing Firm you can!

Many fields of engineering require visits to machine shops. Ties were always tucked into the buttons of your shirt in those cases. When you took it back out it always looked a little ... odd. That's likely the inspiration for Dilbert's perpetually upturned tie - even though he's a computer jock.

"The six models announced in April of 1964 had a performance range of roughly 25-to-1, with the largest model being about 25 times more powerful than the smallest. The smallest model could perform 33,000 additions per second; the largest more than 750,000 additions per second."

I love that the computers then were categorized by size!

"My mainframe is bigger than yours is!"

Though to be fair I still remember the days when, all else being equal, a "Full Size Tower" PC was more impressive than a "Mid Size Tower" (and forget about those crappy Mini Towers!).

"Take men to the moon." Not bring. I expect my friends to not know the difference, the state of American's command of the English language being what it is today. But a professionally edited journal should at least get it right in the headline, for crying out loud.

If I remember correctly the computations for lunar orbit trajectories couldn't be done in anything like real time. The over-night time was used to compute and store possible variants should they be needed.

I was told this at Johnson Spaceflight Center at some point in the 70s.

Just remember, some of those disk drives might have held 500 MB! Or less. Mass storage was very expensive and core was equisitely more-so.

Does anyone have a sense for what these machines were used for? What was the workflow exactly? I understand what NASA would be doing, simulating models with differential equations and such, but what did corporations use hem for? What kind of information is stored on those giant magnetic reels in 1966, and what did the computer do with it on a day to day basis?

ATTENTION!ALL tourists as NONTEKNISCHEN LOOKENPEEPERS!THIS IS NOT FOR THE KOMPUTERMASCHINE GEFINGERPOKEN AND MIDDLE DITCH! ODERWISE IS EASY TO SNAP THE JUMPING PLANT, AND BLOWENFUSEN POPPENCORKEN WITH LACE Sparken.IS NOT FOR trades AT STUPID heads. THE RUBBER CORNER SIGHTSEEREN KEEPEN THE COTTON PICK IN THE POCKETS MUST handers.ZO RELAX AND THE FLASHING WEIGHING slaps.

Modern IBM mainframes go by the name System z, which maintains compatibility all the way back to System/360. "The need to support applications of varying ages imposes a strict compatibility demand on mainframe hardware and software, which have been upgraded many times since the first System/360 mainframe computer," IBM says. "Applications must continue to work properly. Thus, much of the design work for new hardware and system software revolves around this compatibility requirement."

The result is that "Programs for the original System/360s can still run, sometimes with only slight modification, on IBM mainframes today," IDG News Service reporter Joab Jackson noted. While complete compatibility over many decades and system changes isn't possible, IBM tries to give users at least a year's warning before they'd need to make software changes.

That's what I find most impressive out of anything.50 years of backwards compatibility.

Agreed. I think that's one aspect modern computers could learn from.

I agree that it's impressive, but not necessarily that modern computers should aim for this.

Backwards compatibility comes at a development expense and limits what can be done with new hardware and software.

A good tradeoff for these mission critical systems that need to support old software? Yes.

A good tradeoff so that you can more easily play games of yesteryear or use an old copy of Photoshop? Not necessarily.

"Take men to the moon." Not bring. I expect my friends to not know the difference, the state of American's command of the English language being what it is today. But a professionally edited journal should at least get it right in the headline, for crying out loud.

I couldn't help but think of Harlan Ellison's rant about how Star Trek's "To Boldly Go" really should be "To Go Boldly."

The ties are a little narrow but the suits still look good, fifty years later.

With tiepins as a mandatory accessory - one time when our Prime mini was being serviced by the duly authorized & expensive man a jovial executive from our side leaned over for a look, his un-pinned tie dangling into the works. Serviceman yelled with horror - nice dry aircon so many kV of static electricity across tie about to slap around a board of big leggy CMOS chips. Us lowly operators were most impressed - didn't know you even could yell at our execs and live, but when you're from a Big Computing Firm you can!

I still have a bunch of my Dad's tie tacks. He continued wearing them until he retired in the early 90's.

i would have loved to read about the current uses for these beasts. while the market for the z series has shrunk considerably, not all of them are running legacy code. also, the linux personality on these has gotten quite a bit of traction.

i would have also liked to read more about all the concepts we use now, that first were commercially available on mainframes. i can still hear the snickering of the mainframe guys when the first unix people showed up and talked about virtualization.

and of course, a look at the architecture would have been nice. they are still doing plenty of interesting things there.

and then there's the whole maintainability thing. pulling out cpu boards on a running system and other fun stuff. not that isn't available on other systems these days, but they did that fairly early as well.

and do keep wondering about the power/thermal profile of a current z series in comparison to a competitively scaled cluster of x86 boxes.

and no, i don't work for IBM, nor am i a big fan of the company. but credit where credit is due, i say.

Does anyone have a sense for what these machines were used for? What was the workflow exactly? I understand what NASA would be doing, simulating models with differential equations and such, but what did corporations use hem for? What kind of information is stored on those giant magnetic reels in 1966, and what did the computer do with it on a day to day basis?

All computers are essentially fancy calculators. However, they run so many calculations a minute they can figure out complex mathematical problems involving things like speed and trajectory in a fraction of the time it would take a traditional engineer to do with a slide rule (anyone remember slide rules?).

On top of that, financial transactions can be done much more quickly with a computer than an abacus. It takes a lot of manpower to reconcile bank transactions, especially when your bank is so large it does thousands of them every day: every thing from personal checking acounts, to payroll acounts, to stock accounts and tracking the stock market.

Tape reels were the hard drives of the day. They performed the exact same purpose of your magnetic or flash (solid state) hard drive today. Before tape drives, they had punch cards.

Does anyone have a sense for what these machines were used for? What was the workflow exactly? I understand what NASA would be doing, simulating models with differential equations and such, but what did corporations use hem for? What kind of information is stored on those giant magnetic reels in 1966, and what did the computer do with it on a day to day basis?

All computers are essentially fancy calculators. However, they run so many calculations a minute they can figure out complex mathematical problems involving things like speed and trajectory in a fraction of the time it would take a traditional engineer to do with a slide rule (anyone remember slide rules?).

On top of that, financial transactions can be done much more quickly with a computer than an abacus. It takes a lot of manpower to reconcile bank transactions, especially when your bank is so large it does thousands of them every day: every thing from personal checking acounts, to payroll acounts, to stock accounts and tracking the stock market.

Tape reels were the hard drives of the day. They performed the exact same purpose of your magnetic or flash (solid state) hard drive today. Before tape drives, they had punch cards.